And more to the point, /usr isn't supposed t be needed until you are past the point of mounting all filesystems so you can boot from something tiny. Doesn't modprobe need its files earlier than that?
I think that a lot of these objections are addressed here:
http://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken/
Great. And it's from freedesktop... as opposed to, say, a system user, and which implies to me that it's for runlevel 5 GUI-only users....
perhaps you should read links before you make assumptions. and doubly so before you start following up.